btrfs-progs: kill BUG_ON in readahead_tree_block()

David sent a quick patch that removed a BUG_ON().  I took a peek and
found that the function was already leaking an eb ref and only returned
0.  So this fixes the leak and makes the function void and fixes up the
callers.

Accidentally-motivated-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Zach Brown <zab@zabbo.net>
Signed-off-by: David Sterba <dsterba@suse.cz>

3 files changed, 13 insertions, 21 deletions

diff --git a/cmds-check.c b/cmds-check.c
index 268e588f..d479361a 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -1287,7 +1287,6 @@ static void reada_walk_down(struct btrfs_root *root,
 	u32 nritems;
 	u32 blocksize;
 	int i;
-	int ret;
 	int level;
 
 	level = btrfs_header_level(node);
@@ -1299,9 +1298,7 @@ static void reada_walk_down(struct btrfs_root *root,
 	for (i = slot; i < nritems; i++) {
 		bytenr = btrfs_node_blockptr(node, i);
 		ptr_gen = btrfs_node_ptr_generation(node, i);
-		ret = readahead_tree_block(root, bytenr, blocksize, ptr_gen);
-		if (ret)
-			break;
+		readahead_tree_block(root, bytenr, blocksize, ptr_gen);
 	}
 }
 
diff --git a/disk-io.c b/disk-io.c
index f71f5ca7..1f1ce75f 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -134,31 +134,26 @@ struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
 				   blocksize);
 }
 
-int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
-			 u64 parent_transid)
+void readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
+			  u64 parent_transid)
 {
-	int ret;
 	struct extent_buffer *eb;
 	u64 length;
 	struct btrfs_multi_bio *multi = NULL;
 	struct btrfs_device *device;
 
 	eb = btrfs_find_tree_block(root, bytenr, blocksize);
-	if (eb && btrfs_buffer_uptodate(eb, parent_transid)) {
-		free_extent_buffer(eb);
-		return 0;
+	if (!(eb && btrfs_buffer_uptodate(eb, parent_transid)) &&
+	    !btrfs_map_block(&root->fs_info->mapping_tree, READ,
+			     bytenr, &length, &multi, 0, NULL)) {
+		device = multi->stripes[0].dev;
+		device->total_ios++;
+		blocksize = min(blocksize, (u32)(64 * 1024));
+		readahead(device->fd, multi->stripes[0].physical, blocksize);
 	}
 
-	length = blocksize;
-	ret = btrfs_map_block(&root->fs_info->mapping_tree, READ,
-			      bytenr, &length, &multi, 0, NULL);
-	BUG_ON(ret);
-	device = multi->stripes[0].dev;
-	device->total_ios++;
-	blocksize = min(blocksize, (u32)(64 * 1024));
-	readahead(device->fd, multi->stripes[0].physical, blocksize);
+	free_extent_buffer(eb);
 	kfree(multi);
-	return 0;
 }
 
 static int verify_parent_transid(struct extent_io_tree *io_tree,
diff --git a/disk-io.h b/disk-io.h
index 13d4420a..c2960558 100644
--- a/disk-io.h
+++ b/disk-io.h
@@ -48,8 +48,8 @@ struct btrfs_device;
 int read_whole_eb(struct btrfs_fs_info *info, struct extent_buffer *eb, int mirror);
 struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 				      u32 blocksize, u64 parent_transid);
-int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
-			 u64 parent_transid);
+void readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
+			  u64 parent_transid);
 struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
 						   u64 bytenr, u32 blocksize);